Method for Fabricating Blackened Conductive Patterns

ABSTRACT

The present invention relates to a method for fabricating blackened conductive patterns, which includes (i) forming a resist layer on a non-conductive substrate; (ii) forming fine pattern grooves in the resist layer using a laser beam; (iii) forming a mixture layer containing a conductive material and a blackening material in the fine pattern grooves; and (iv) removing the resist layer remained on the non-conductive substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/747,331, filed Sep. 20, 2010, entitled “Method for FabricatingBlackened Conductive Patterns”, which is the United States NationalPhase of International Patent Application No. PCT/KR2008/007307, filedDec. 10, 2008, which claims the priority of Korean Patent ApplicationNo. 10-2007-0128149, filed Dec. 11, 2007, each of which is herebyincorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a method for fabricating blackenedconductive patterns, and more particularly, to a method for fabricatingblackened conductive patterns in which a resist layer is formed on anon-conductive substrate using polymer material, fine pattern groovesare formed on the resist layer using a laser beam and then, theblackened conductive patterns are formed in the fine pattern grooves.

BACKGROUND ART

Blackening is generally used, for the purpose of increasing visibility,as a method for roughening (diffusion of light) or blackening(absorption of light) a surface of a metal layer by treating with acidor alkali or by plating to eliminate scattered reflection of light andraise light absorption. For example, if a blackened layer is formed on ametal mesh for shielding electromagnetic wave generated from a PDP,reflection of light from the electromagnetic shielding metal isinhibited and an image on the display can be therefore seen with highcontrast.

Currently commercialized methods of forming blackened conductivepatterns can be representatively divided into a photolithographic methodand a screen printing method. In the photolithographic method, aflexible base film made by pressing a thin plate of conductive materialonto a polyethylene (PE) or polyester (PET) film is used. In order toform a pattern circuit, a dry film or a photoresist solution is coatedon the surface of the conductive material and a film to be realized tothe circuit is compacted onto the dry film or photoresist solutioncoated layer, followed by UV irradiation, thereby transferring thecircuit. After development using a developing solution, unnecessaryconductive thin plate is etched using a chemical etching solution withthe circuit to be realized alone being remained, and the dry film orcoated photoresist solution compacted on the surface of the circuit isthen removed to fabricate patterns. The resulting conductive patternsare brought into contact with blackening material to form blackenedconductive patterns.

However, the aforementioned conventional photolithography method hasproblems that the fabrication process is complex and winding, crumplingor tearing may be generated due to an adhesive layer used for the filmduring transporting process of the fabrication. Also, high cost andlarge sized equipments are required according to the etching process andenvironmental problem may be caused during disposal of the etchingsolution.

In the screen printing, another method of forming and blackeningconductive patterns, a conductive paste is screen printed to formconductive patterns and thereon blackening material is formed or aconductive paste containing the blackening material is screen printed,thereby forming the blackened conductive patterns. The method ofconductive patterns by the screen printing has simple processes, butrepresents limitation to form high resolution patterns of below 30 umand large area patterns and also has problems of high cost equipment andlow productivity.

In recent, in order to form the high resolution patterns of below 30 um,there has been studied a method using a laser.

Japanese Patent Publication No. 2002-314227 discloses a method formanufacturing a ceramic circuit board, in which holes corresponding toconductive patterns is formed on a film adhered to a green sheet bylaser processing, a conductive paste is filled in the through hole andthereafter the film adhered to the green sheet is removed, therebyforming thin fine conductive patterns. Japanese Patent Publication No.2004-281738 discloses a method for drawing conductive wire patterns byadhering a conductive paste to a substrate through laser scanning, inwhich the surface of a the substrate on which a conductive paste iscoated is scanned by laser beams to form conductive wire patters bycuring the conductive paste and thereafter the portion of the conductivepaste excluding the portion scanned by the laser beams is solved by anorganic solvent to removed the same and the portion scanned by the laserbeams is then calcined to draw conductive the wire patterns on thesubstrate.

Japanese Patent Publication No. 2006-222295 discloses a method forultrafine wiring board on which ultrafine wirings are formed, in which aphotoresist resin formed on a board is subject to an interferenceexposure by irradiating a laser beam, followed by development, andthereafter, a solution containing conductive material is filled in thebottom of the groove portion and sintered, thereby forming ultrafinewirings.

Also, US Patent Publication No. 20060057502 discloses a conductivewiring pattern by laser irradiation, in which a board is applied withmetal dispersion colloid including metal nanoparticles of 0.5 nm-200 nmdiameters, a dispersion agent and a solvent, partially irradiated by alaser beam of 300 nm-550 nm wavelengths to sinter the metalnanoparticles and then washed to eliminate metal dispersion colloid onthe portion not irradiated by the laser beam, thereby forming theconductive circuit corresponding to the shape irradiated by the laserbeam.

Although various methods of forming fine patterns using a laser aredisclosed as described above, a method of forming blackened finepatterns has not yet been disclosed.

DISCLOSURE Technical Problem

The present inventors have achieved the present invention as the resultof constant studies for solving the various problems in the conventionalmethod of blackening conductive patterns.

An object of the present invention is to provide a method forfabricating blackened conductive pattern, in which fabrication processis simple and economic, an environmental problem due to disposal of anetching solution is not generated and fine blackened conductive patternswith high resolution and superior conductivity and blackened degree canbe fabricated.

Technical Solution

The present invention according to the present invention ischaracterized by forming the blackened conductive pattern by forming aresist layer using polymer material, forming fine pattern grooves usinga laser beam, a mixture layer containing conductive material andblackening material in the fine grooves and removing the resist layer.

A method for fabricating blackened conductive pattern according to thepresent invention includes (i) forming a resist layer on anon-conductive substrate (S10); (ii) forming fine pattern grooves in theresist layer using a laser beam (S20); (iii) forming a mixture layercontaining a conductive material and a blackening material in the finepattern grooves (S30); and (iv) removing the resist layer remained onthe non-conductive substrate (S40).

Hereinafter, the present invention will be described in more detail bythe steps.

Step (i): Forming a Resist Layer on a Non-Conductive Substrate

Examples usable for the non-conductive substrate may include a glassboard or a plastic film made of polyimide (PI), polyethyleneterephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone(PES), Nylon, polytetrafluoroethylene (PTFE), polyetheretherketone(PEEK), polycarbonate (PC) or polyarylate (PAR), but not limitedthereto. The substrate may be selectively used to meet the properties ofthe substrate according to a heat treating temperature which will bedescribed later.

The material for forming the resist layer is preferred to be readilyvaporized or decomposed by a laser beam and not to dissolve theconductive material. The usable material is an organic polymer materialand examples for the an organic polymer material may includepolypropylene, polycarbonate, polyacrylate, polymethylmethacrylate,cellulose acetate, polyvinyl chloride, polyurethane, polyester, alkydresin, epoxy resin, melamine resin, phenol resin, phenol modified alkydresin, epoxy modified alkyd resin, vinyl modified alkyd resin, siliconemodified alkyd resin, acrylic melamine resin, polyisocyanate resin andepoxy ester resin, but not particularly limited thereto, provided thatthe object of the present invention can be achieved.

As the method of forming the resist layer on the non-conductivesubstrate, a known conventional method of forming a layer may be used,but the method is not particularly limited, provided that the object ofthe present invention can be achieved. For example, spin coating, rollcoating, spray coating, dip coating, flow coating, doctor blade anddispensing, inkjet printing, offset printing, screen printing, padprinting, gravure printing, flexography printing, stencil printing,imprinting or the like may be used.

Also, a solvent may be used to form the resist layer to a uniform thinfilm. Examples for the solvent may include alcohols such as ethanol,isopropanol and butanol, glycols such as ethylene glycol and glycerine,acetates such as ethyl acetate, butyl acetate, methoxypropyl acetate,carbitol acetate and ethylcarbitol acetate, ethers such as methylcellosolve, butyl cellosolve, diethyl ether, tetrahydrofuran anddioxane, ketones such as methyl ethyl ketone, acetone,dimethylformaldehyde and 1-methyl-2-pyrrolidone, hydrocarbons such ashexane, heptane, dodecane, paraffin oil and mineral spirit, aromatichydrocarbons such as benzene, toluene and xylene, halogen substitutedsolvent such as chloroform, methylene chloride and carbon tetrachloride,acetonitrile, dimethyl sulfoxide or a mixture thereof.

The resist layer is formed to a thickness of below 50 μm, preferably 1μm to 25 μm. The thickness of the resist layer is required to becontrolled according to the condition for the formation of single layerpatterns or multilayer patterns.

Upon the formation of the resist layer, dry may be performed at atemperature range in which the non-conductive substrate is not deformed,preferably at 80 to 400° C.

Step (ii): Forming Fine Pattern Grooves in the Resist Layer

A method of forming fine pattern grooves in the state that the resistlayer is formed on the non-conductive layer with a uniform thickness isto utilize a laser beam having energy enough to vaporize or decomposethe material of the resist layer. When using the laser beam, it ispossible to form a fine circuit with high resolution. It is alsopossible to vaporize or decompose some of the substrate other than theresist layer.

In the present invention, it is possible to realize the resolution ofthe fine patterns to a minimum critical dimension which can be directlypatterned by a laser beam. The minimum critical dimension may besub-micrometer and the maximum critical dimension may be hundreds tothousands micrometers according to a laser equipment. Also, it ispossible to a height of the fine pattern groove by controlling theoutput energy of the laser beam. It is possible to control the height ofthe fine pattern groove from minimally sub-micrometer to maximally overthe thickness of the resist layer to the thickness of the non-conductivesubstrate. In addition, it is possible to control the height of the finepattern groove and a thickness of the blackened conductive patternfinally formed in the following step according to a method of formingand blackening the conductive patterns. Furthermore, it is possible toform the fine patterns partially using an optical diffraction element ora mask in order to control the shape of the beam advantageously to thepatterning upon the use of the laser beam.

Step (iii): Forming a Mixture Layer Containing a Conductive Material anda Blackening Material in the Fine Pattern Grooves

The mixture layer containing the conductive material and the blackeningmaterial may be a single layer in which the conductive material and theblackening material are mixed, a stacked layer in which a conductivelayer containing the conductive material and a blackened layercontaining the blackening material are stacked in turn or a mixturelayer structured so that the blackened layer surrounds the conductivelayer.

The method of forming the mixture layer will be described in detail.

First, the mixture layer may be formed by filling a conductive inkcontaining the blackening material and the conductive material in thefine pattern grooves.

Second, the mixture layer may be formed by forming a conductive layer byfilling and drying a conductive ink containing the conductive materialin the fine pattern grooves and forming an upper blackened layer on theconductive layer.

Third, the mixture layer may be formed by forming a lower blackenedlayer by filling and drying a blackening solution containing theblackening material in the fine pattern grooves, forming a conductivelayer by filling and drying a conductive ink containing the conductivematerial in the fine pattern grooves formed with the lower blackenedlayer, and forming an upper blackened layer on the conductive layer. Themixture layer may have a structure in that the conductive layer issurrounded by the lower blackened layer and the upper blackened layer.

The upper blackened layer formed on the conductive layer may be formedby filling the blackening solution containing the blackening material inthe fine pattern groove formed with the conductive layer and drying theblackening solution, by electroplating or electroless plating theblackening material on the conductive layer or by dipping the conductivelayer formed in the fine pattern grooves in a blackening solutioncontaining the blackening material to blacken the surface of theconductive layer.

The conductive material is not particularly limited and includesgenerally used material. For example, silver, gold, platinum, palladium,copper, nickel, zinc, iron, aluminum or a mixture thereof may be used.

Also, the shape of the conductive material may be spherical, linear,platy or a mixed shape thereof and may be used in various formsincluding particles, powder, flakes, colloid, hybrid, paste, sol,solution which include nanoparticles, or a mixture of at least twothereof.

The present inventors had applied a method for preparing silvernanoparticles by reducing silver complex with a specific structure asKorean Patent Application No. 2006-0074246. The conductive materialaccording to the present invention may contain the silver nanoparticlesprepared by the above Patent Application. The silver nanoparticlesdisclosed in the above Patent Application have advantages of uniformparticle size and minimized cohesion and a conductive ink including thesilver nanoparticles has an advantage that it is possible to readilyform uniform and dense thin film or fine pattern even when the ink hasbeen calcined for a short time at a low temperature of below 150° C. Inthe present invention, advantages of easy formation of the conductivepatterns and superior physical properties of the formed patterns areresulted when the conductive material according to the present inventionincludes the silver nanoparticles prepared by the following fabricationmethod as described in the above Patent Application:

a) forming a silver complex by reacting a silver compound represented bythe formula 1 below with one or a mixture of two or more selected fromthe group consisting of ammonium carbamate-based compound, ammoniumcarbonate-based compound and ammonium bicarbonate-based compoundrepresented by the formula 2 to 4 below; and

b) preparing silver nanoparticles by reducing or thermally decomposingthe silver complex prepared in the step a) by reacting the silvercomplex with a reducing agent or applying heat to the silver complex,

wherein, in the formulas 1 to 4, X is a substituent selected from thegroup consisting of oxygen, sulfur, halogen, cyano, cyanate, carbonate,nitrate, nitrite, sulfate, phosphate, thiocyanate, chlorate,perchlorate, tetrafluoroborate, acetylacetonate, carboxylate andderivatives thereof, n is an integer from 1 to 4, and R₁ to R₆ areindependently selected from the group consisting of hydrogen, hydroxylgroup, C₁-C₃₀ alkoxy group, C₃-C₂₀ aryloxy group, C₁-C₃₀ aliphatic orC₃-C₂₀ cycloaliphatic alkyl group or C₃-C₂₀ aryl or C₄-C₃₀ aralkyl groupas a mixture thereof, substituted C₁-C₃₀ alkyl group, substituted C₁-C₂₀aryl group, substituted C₄-C₃₀ aralkyl group, C₃-C₂₀ heterocycliccompound including a heteroatom selected from the group consisting of N,S, O, polymer compound and derivatives thereof, wherein when R₁ to R₆are substituted or unsubstituted alkyl group or aralkyl group, alkylgroup or aralkyl group may contain a heteroatom selected from the groupconsisting of N, S, O or an unsaturated bond in the carbon chain,wherein R₁ and R₂ or R₄ and R₅, independently, may form an alkylene ringcontaining or not containing a heteroatom.

Examples for the substituted functional group may include, but notlimited to, C₁-C₃₀ alkoxy group, carboxyl group, tri(C₁-C₇)alkoxysilylgroup, hydroxyl group and cyano group.

Specific examples for the compound of the formula 1 are, but not limitedto, silver oxide, silver thiocyanate, silver sulfide, silver chloride,silver cyanide, silver cyanate, silver carbonate, silver nitrate, silvernitrite, silver sulfate, silver phosphate, silver perchlorate, silvertetrafluoroborate, silver acetylacetonate, silver acetate, silverlactate, silver oxalate or a derivative thereof.

Also, specific examples for the substituents R₁ to R₆ of the formulas 2to 4 may be selected from, but not particularly limited to, the groupconsisting of hydrogen, methyl, ethyl, propyl, isopropyl, butyl,isobutyl, amyl, hexyl, ethylhexyl, heptyl, octyl, isooctyl, nonyl,decyl, dodecyl, hexadecyl, octadecyl, docodecyl, cyclopropyl,cyclopentyl, cyclohexyl, allyl, hydroxy, methoxy, hydroxyethyl,methoxyethyl, 2-hydroxypropyl, methoxypropyl, cyanoethyl, ethoxy,butoxy, hexyloxy, methoxyethoxyethyl, methoxyethoxyethoxyethyl,hexamethyleneimine, morpholine, piperidine, piperazine, ethylenediamine,propylenediamine, hexamethylenediamine, triethylenediamine, pyrrole,imidazole, pyridine, carboxymethyl, trimethoxysilylpropyl,triethoxysilylpropyl, phenyl, methoxyphenyl, cyanophenyl, phenoxy,tolyl, benzyl and a derivative thereof, a polymer compound such aspolyallylamine and polyethyleneimine and a derivative thereof.

In specific examples for the compound, the ammonium carbamate-basedcompound represented by the formula 2 may be one or a mixture of two ormore selected from the group consisting of ammonium carbamate,ethylammonium ethylcarbamate, isopropylammonium isopropylcarbamate,n-butylammonium n-butylcarbamate, isobutylammonium isobutylcarbamate,t-butylammonium t-butylcarbamate, 2-ethylhexylammonium2-ethylhexylcarbamate, octadecylammonium octadecylcarbamate,2-methoxyethylammonium 2-methoxyethylcarbamate, 2-cyanoethylammonium2-cyanoethylcarbamate, dibutylammonium dibutylcarbamate,dioctadecylammonium dioctadecylcarbamate, methyldecylammoniummethyldecylcarbamate, hexamethyleneiminium hexamethyleneiminecarbamate,morpholinium morpholinecarbamate, pyridinium ethylhexylcarbamate,triethylenediaminium isopropylbicarbamate, benzylammoniumbenzylcarbamate, triethoxysilylpropylammoniumtriethoxysilylpropylcarbamate and a derivative thereof. The ammoniumcarbonate-based compound represented by the formula 3 may be may be oneor a mixture of two or more selected from the group consisting ofammonium carbonate, ethylammonium ethylcarbonate, isopropylammoniumisopropylcarbonate, n-butylammonium n-butylcarbonate, isobutylammoniumisobutylcarbonate, t-butylammonium t-butylcarbonate,2-ethylhexylammonium 2-ethylhexylcarbonate, 2-methoxyethylammonium2-methoxyethylcarbonate, 2-cyanoethylammonium 2-cyanoethylcarbonate,octadecylammonium octadecylcarbonate, dibutylammonium dibutylcarbonate,dioctadecylammonium dioctadecylcarbonate, methyldecylammoniummethyldecylcarbonate, hexamethyleneiminium hexamethyleneiminecarbonate,morpholinium morpholinecarbonate, benzylammonium benzylcarbonate,triethoxysilylpropylammonium triethoxysilylpropylcarbonate,triethylenediaminium isopropylcarbonate and a derivative thereof. Theammonium bicarbonate-based compound represented by the formula 4 may bemay be one or a mixture of two or more selected from the groupconsisting of ammonium bicarbonate, isopropylammonium bicarbonate,t-butylammonium bicarbonate, 2-ethylhexylammonium bicarbonate,2-methoxyethylammonium bicarbonate, 2-cyanoethylammonium bicarbonate,dioctadecylammonium bicarbonate, pyridinium bicarbonate,triethylenediaminium bicarbonate and a derivative thereof.

The conductive ink containing conductive material according to thepresent invention contains at least one conductive material and mayinclude, if necessary, additives such as a solvent, a stabilizer, adispersant, a binder resin, a reducing agent, a glass frit, asurfactant, a wetting agent, a thixotropic agent and a leveling agent.

The drying temperature of the conductive ink is generally 100 to 300°C., preferably 100 to 200° C., which is good for physical properties ofthe thin film. Calcination may be performed when forming the mixturelayer or the conductive layer. But, it is preferred to perform thecalcination process in the step of removing the resist layer because thecalcinations of the mixture layer and the removal of the remained resistlayer can be performed at the same time. A filling thickness of theconductive material is determined by the content of solids aftervolatilization of the solvent in the conductive ink. The fillingthickness of the conductive material is preferably 1 to 80% of athickness of the fine patterns and more preferably 10 to 70%.

The blackening material according to the present invention is used forenhancing a blackened degree of the conductive patterns and may be ametal oxide, a metal sulfide or an organic metal compound containing oneor more than two metal(s) selected from the group consisting of Cu, Zn,Ni, Co, Ti, Mn, Fe, Cr, Nb, Ru, Cd, Ge and Sn. Specific examples may becobalt oxide, chromium oxide, titanium oxide, ruthenium oxide, cobaltstearate, nickel naphthalate, cobalt naphthalate, copper2-ethylhexanoate, tin 2-ethylhexanoate, cobalt hydroxy neodecanoate,iron stearate, nickel formate, calcium naphthenate, zinc citrate, bariumneodecanoate or a mixture of one or more than two thereof. In the stepof forming the mixture layer, a blackening solution containing theblackening material is used. The blackening solution contains a solventin addition to the blackening material and may further contain, ifnecessary, additives such as a stabilizer, a dispersant, a binder resin,a reducing agent, a surfactant, a glass frit, a wetting agent, athixotropic agent and a leveling agent.

As the method of filling the conductive ink or the blackening solutionin the fine pattern grooves upon the formation of the mixture layeraccording to the present invention, a known conventional method offorming a layer may be used, but the method is not particularly limited,provided that the object of the present invention can be achieved. Forexample, spin coating, roll coating, spray coating, dip coating, flowcoating, doctor blade and dispensing, inkjet printing, offset printing,screen printing, pad printing, gravure printing, flexography printing,stencil printing, imprinting or the like may be used. Also, it ispossible to blacken the conductive patterns not only by the formation ofsingle layer patterns but also by the formation of multilayer patterns.

When the solvent contained in the blackening solution is volatilizedafter filling the blackening solution, the filling thickness of theblackened layer is determined according the content of the solids. Thethickness of the blackened layer in the fine pattern grooves ispreferably 1 to 50% of the thickness of the fine patterns and morepreferably 1 to 30%.

The dry after filling the blackening solution may be performed at anytemperature provided that there is no deformation of the polymermaterial in the resist layer.

As described above, in the mixture layer containing the conductivematerial and the blackening material, after the lower blackened layer isformed by the blackening solution, the fine pattern grooves are filledwith the conductive ink, followed by drying the conductive ink, and thenfilled again with the blackening solution to form the upper blackenedlayer, thereby completing formation and blackening of the conductivepatterns. In another example, the fine pattern grooves are sequentiallyfilled with the blackening solution which can raise the blackened degreeand the conductive solution and then heat treated, followed by formationof the blackened surface layer using electroplating or electrolessplating, thereby capable of forming the blackened conductive pattern.

Detailed description will be followed with reference to accompanyingdrawings.

Step (iv): Removing the resist layer remained on the non-conductivesubstrate

By removing the resist layer remained on the substrate after forming themixture layer containing the conductive material and the blackeningmaterial, it is possible to remove the conductive material or theblackening material, which is remained in an unnecessary portion on theresist layer, together.

In the present invention, the resist layer can be removed by using asolvent if the material of the resist layer can be dissolved by asuitable solvent, or by heat treatment for certain time and followingsimple washing using a solvent if the material of the resist layer canbe vaporized or thermally decomposed by heat.

The heat treatment is preferably performed at a temperature of 300 to650° C. and more preferably at a temperature of 500 to 650° C. for theclear removal of the resist layer. During the heat treatment,calcination of the conductive material present in a dry state can beperformed at the same time.

DESCRIPTION OF DRAWINGS

The above and other objects, features and advantages of the presentinvention will become apparent from the following description ofpreferred embodiments given in conjunction with the accompanyingdrawings, in which:

FIG. 1 illustrates the process step of fabricating blackened conductivepatterns related to Example 1 of the present invention;

FIG. 2 illustrates the process step of fabricating blackened conductivepatterns related to Example 2 of the present invention;

FIG. 3 illustrates the process step of fabricating blackened conductivepatterns related to Example 3 of the present invention;

FIG. 4 illustrates the process step of fabricating blackened conductivepatterns related to Examples 4 to 8 of the present invention; and

FIG. 5 illustrates the process step of fabricating blackened conductivepatterns according to further another embodiment of the presentinvention, in which there is no height difference between the blackenedconductive patterns and a substrate.

DETAILED DESCRIPTION OF MAIN ELEMENTS

-   -   10, 20, 30, 40, 60: substrate    -   11, 21, 31, 41, 61: resist layer    -   12, 22, 32, 42, 62: fine pattern groove    -   14, 24: blackening conductive ink    -   34, 44, 64: conductive ink    -   36, 46, 66: blackening solution    -   37, 49, 69: upper blackened layer    -   47, 67: lower blackened layer    -   15, 25, 38, 50, 70: residual resist layer

BEST MODE

Hereinafter, a method for fabricating blackened conductive patternsaccording to the present invention will be described in detail withreference to accompanying drawings.

FIGS. 1 and 2 illustrate the process step of forming blackenedconductive patterns using a blackening conductive ink in which ablackening solution and a conductive ink are mixed. A resist layer 11 isformed on a non-conductive substrate 10 and irradiated by a UV laser toform fine pattern grooves 12. Subsequently, a blackening conductive ink14 is filled in the fine pattern grooves 12 and dried, followed by heattreatment to remove the resist layer 15 remained on the non-conductivesubstrate 10 and calcine the conductive ink at the same time, therebyforming blackened conductive patterns.

Herein the drying process for and calcination process for the conductiveink 14 may be performed at the same time.

Meanwhile, in the fabrication method shown in FIG. 2, the resist layeris removed with the fine patterns and, at the same time, the substrate20 is also removed by a predetermined depth during the process offorming the fine pattern grooves 12 by irradiating the UV laser.Consequently, it is possible to enhance the adhesion between theconductive patterns and the substrate.

FIG. 3 illustrates the process step of fabricating blackened conductivepatterns according to another embodiment of the present invention, inwhich a conductive ink and a blackening solution are sequentially filledto form the blackened conductive patterns. A resist layer 31 is formedon a non-conductive substrate 30 and irradiated by a UV laser to formfine pattern grooves 32. Subsequently, a conductive ink 34 is filled inthe fine pattern grooves 32 and dried. Then, the solvent contained inthe conductive ink is volatilized to reduce a thickness of theconductive pattern layer, thereby forming a predetermined space 35 inthe fine pattern grooves.

In the space 35, a blackening solution 36 is filled and dried to form anupper blackened layer 37, followed by heat treatment to remove theresist layer 38 remained on the non-conductive substrate 30 and calcinethe conductive ink at the same time, thereby forming blackenedconductive patterns.

FIG. 4 illustrates the process step of fabricating blackened conductivepatterns according to further another embodiment of the presentinvention, in which a conductive ink and a blackening solution aresequentially filled to form the blackened conductive patterns. A resistlayer 41 is formed on a non-conductive substrate 40 and irradiated by aUV laser to form fine pattern grooves 42. A blackening solution 46 isfilled in the fine pattern grooves 42 and dried to form a blackenedlayer (a lower blackened layer 47) inside the fine pattern grooves byvolatilization of a solvent contained in the blackening solution.Subsequently, a conductive ink 44 is filled in the fine pattern grooves42 and dried. Then, the solvent contained in the conductive ink isvolatilized to reduce a thickness of the conductive pattern layer,thereby forming a predetermined space 48 in the fine pattern grooves.

In the space 48, the blackening solution is filled and dried to form ablackened layer (an upper blackened layer 47), followed by heattreatment to remove the resist layer 50 remained on the non-conductivesubstrate 40 and calcine the conductive ink at the same time, therebyforming blackened conductive patterns. While the upper blackened layercan be formed by the layer formation method as described above, it ispossible to form the upper blackened layer by electroplating orelectroless plating in a blackening metal solution or dipping in ablackening solution.

Meanwhile, in the fabrication method shown in FIG. 5, during the processof forming the fine pattern grooves 62 by irradiating the UV laser, theresist layer is removed with the fine patterns and, at the same time,the substrate 60 is also removed by a predetermined depth, wherein thedepth of the removed substrate is controlled equal to the height of themixture layer containing the conductive material and the blackeningmaterial which is formed in the subsequent step.

Consequently, it is possible to enhance the adhesion between theconductive patterns and the substrate. In addition, it is also possibleto form even blackened conductive patterns having no height differencefrom the surface of the substrate since the blackened conductive patternlayer is formed in a damascene manner.

Preparation Example 1 Preparation of Silver Complex

Into a 250 ml Schlenk flask equipped with a stirrer, 34.89 g (129.8mmol) of viscous liquid in which 2-ethylhexylammonium2-ethylhexylcarbamate and butylammonium butylcarbamate are mixed at amolar ratio of 7:3 was put and 12.03 g (51.92 mmol) of silver oxide(made by Aldrich Chemical Co.) was added, followed by the reaction atroom temperature for two hours with stirring. The reaction solution wasinitially a black slurry, but it turned transparent as complex wasproduced. Finally, 46.92 g of yellow, transparent aqueous silver complexwas obtained and the silver complex had a viscosity of 7.8 pa·s and asilver content of 23.65 wt % (TGA analysis)

Preparation Example 2 Preparation of Silver Nanoparticles

Into a 100 ml beaker, 40.0 g of the silver complex prepared inPreparation Example 1 and 23.1 g of isopropyl alcohol were added andstirred at room temperature for ten minutes to prepare a first solution.Into another 100 ml beaker, 1.2 g of hydrazine monohydrate (made byDaejung Chemicals and Metals Co. Ltd.) and 50 g of isopropyl alcoholwere added to prepare a second solution. The first solution and thesecond solution were injected into their inlets with a flow rate of 20g/min, respectively. The solutions injected through the inlets werereacted at 5,000 rpm using a stirrer (made by Silverthorne, productname: L4RT-A) to obtain dark green slurry. The prepared slurry wasfiltered with a 1.2 um filter (made by Wattman company, product name:GF/C) by natural precipitation, followed by washing three times withisopropyl alcohol to obtain green nonopowder.

Preparation Example 3 Preparation of Conductive Ink

To 1.2 g of terpineol (made by TCI) as a solvent having a high boilingpoint, 40.0 g of the silver complex prepared by the same manner asdescribed in Preparation Example 1 and 40 g of the green nanopowderprepared by the same manner as described in Preparation Example 2 wereadded and stirred for ten minutes, followed by adding 1.2 g of1-amino-2-propanol (made by Aldrich Chemical Co.) and stirring again fortem minutes. After that, the resultant was passed through a three rollmill (made by Drais Manheim) three times to prepare a conductive inkcomposition having a silver content of 59.93 wt %.

Preparation Example 4 Preparation of Blackening Solution

To 46.5 g of terpineol (made by TCI) as a solvent having a high boilingpoint, 12 g of cobalt oxide (made by Junsei)), 30 g of glass frit (madeby Daion), 1.5 g of EFKA 4300 (made by EFKA) and 10 g of BR18 (made byWacker) were added and stirred for ten minutes. After that, theresultant was passed through a three roll mill (Drais Manheim) threetimes to prepare a blackening solution composition.

Example 1

3 g of acryl resin (E 2823, made by Elvacite) was dissolved in 1 g oftoluene and 0.2 g of butyl acetate to prepare an ink for screen printingof a resist layer. The ink was screen printed onto a glass substrate toform a resist layer pattern having a thickness of 10 micrometers. Next,a region to be formed with blackened conductive patterns was formed onthe resist layer pattern using a UV laser (made by UPI tech, productname: Xpress-DP) with a beam diameter of 20 micrometers. A criticaldimension of the fine pattern was about 20 micrometers, which is similarto the beam diameter of the laser. Next, the conductive ink compositionprepared in Preparation Example 3 and the blackening solutioncomposition prepared in Preparation Example 4 were mixed with a weightratio of 8:2 and filled in the fine pattern using screen printingfollowed by drying at 150 for two minutes. A thickness of the blackenedconductive patterns was 5 micrometers. After that, calcination wasperformed at 600° C. to remove the residual resist layer material,thereby capable of obtaining blackened conductive fine patterns.

Example 2

Blackened conductive fine patterns were obtained by the same manner asin Example 1 except that the groove was formed passing through theresist layer into the glass substrate by a depth of 2 micrometers uponthe formation of the pattern by vaporization of the resist layer usingthe UV laser.

Example 3

3 g of acryl resin (E 2823, made by Elvacite) was dissolved in 1 g oftoluene and 0.5 g of butyl acetate to prepare a coating solution forspin coating of a resist layer.

The coating solution spin coated onto a glass substrate at 500 rpm toform a resist layer having a thickness of 10 micrometers. Next, a regionto be formed with blackened conductive patterns was formed on the resistlayer pattern using a UV laser (made by UPI tech, product name:Xpress-DP) with a beam diameter of 20 micrometers. A critical dimensionof the fine pattern was about 20 micrometers, which is similar to thebeam diameter of the laser. Next, the conductive ink compositionprepared in Preparation Example 3 was filled in the fine pattern usingscreen printing, followed by drying at 150° C. for two minutes. Athickness of the conductive patterns was 5 micrometers. After that, theblackening solution composition prepared in Preparation Example 4 wasfilled on the conductive pattern using screen printing to form an upperblackened layer with a thickness of 1 micrometer, followed bycalcination at 600° C. The material remained as the resist layer wasvaporized upon the calcination at 600° C., thereby capable of obtainingblackened conductive fine patterns by only washing using toluene.

Example 4

3 g of acryl resin (E 2823, made by Elvacite) was dissolved in 1 g oftoluene and 0.2 g of butyl acetate to prepare an ink for screen printingof a resist layer. The ink was screen printed onto a glass substrate toform a resist layer pattern having a thickness of 10 micrometers. Next,a region to be formed with blackened conductive patterns was formed onthe resist layer pattern using a UV laser (made by UPI tech, productname: Xpress-DP) with a beam diameter of 20 micrometers. A criticaldimension of the fine pattern was about 20 micrometers, which is similarto the beam diameter of the laser. Next, the blackening solutioncomposition prepared in Preparation Example 4 was filled in the finepattern using screen printing, followed by drying at 200° C. to form alower blackened layer with a thickness of 1 micrometer. Next, theconductive ink composition prepared in Preparation Example 3 was filledin the fine pattern formed with the lower blackened layer using screenprinting, followed by drying at 150° C. for two minutes. A thickness ofthe conductive patterns was 5 micrometers. After that, the blackeningsolution composition prepared in Preparation Example 4 was filled inusing screen printing to form an upper blackened layer with a thicknessof 1 micrometer, followed by calcination at 600° C. The materialremained as the resist layer was vaporized upon the calcination at 600°C., thereby capable of obtaining blackened conductive fine patterns byonly washing using toluene.

Example 5

3 g of acryl resin 2823, made by Elvacite) was dissolved in 1 g oftoluene and 0.2 g of butyl acetate to prepare a coating solution forscreen printing of a resist layer. The coating solution was screenprinted onto a glass substrate to form a resist layer pattern having athickness of 10 micrometers. Next, a region to be formed with blackenedconductive patterns was formed on the resist layer pattern using a UVlaser (made by UPI tech, product name: Xpress-DP) with a beam diameterof 20 micrometers. A critical dimension of the fine pattern was about 20micrometers, which is similar to the beam diameter of the laser. Next,the blackening solution composition prepared in Preparation Example 4was spin coated at 2500 rpm for 20 seconds to fill in the fine pattern,followed by drying at 200° C. to form a lower blackened layer with athickness of 1 micrometer. Next, the conductive ink composition preparedin Preparation Example 3 was spin coated at 2500 rpm for 20 seconds tofill in the fine pattern, followed by drying at 150° C. for two minutes.A thickness of the conductive patterns was 5 micrometers. After that,the formed fine pattern was dipped in strong hydrochloric acid (35%) forone minute, and then dipped in a copper plating solution [a solutionprepared in 1 L by mixing copper sulfate hydrate (180 g), sulfuric acid(27 g) and ion exchanged water].

In this copper plating solution, an electrolytic copper electrode isdipped, followed by black copper plating by applying a voltage 3 V forthree minutes. A thickness of the black copper plated layer (an upperblackened layer) was 1 micrometer. After that, calcination was performedat 600° C. to remove the residual resist layer material, thereby capableof obtaining blackened conductive fine patterns.

Example 6

3 g of acryl resin (E 2823, made by Elvacite) was dissolved in 1 g oftoluene and 0.2 g of butyl acetate to prepare a coating solution forscreen printing of a resist layer. The coating solution was screenprinted onto a glass substrate to form a resist layer pattern having athickness of 10 micrometers. Next, a region to be formed with blackenedconductive patterns was formed on the resist layer pattern using a UVlaser (made by UPI tech, product name: Xpress-DP) with a beam diameterof 20 micrometers. A critical dimension of the fine pattern was about 20micrometers, which is similar to the beam diameter of the laser. Next,the blackening solution composition prepared in Preparation Example 4was filled in using a bar coater, followed by drying at 200° C. to forma lower blackened layer with a thickness of 1 micrometer.

Next, the conductive ink composition prepared in Preparation Example 3was filled in the fine pattern using a bar coater, followed by drying at150° C. for two minutes. A thickness of the conductive patterns was 5micrometers. After that, the formed fine pattern was dipped in stronghydrochloric acid (35%) for one minute, and then dipped in a copperplating solution [a solution prepared in 1 L by mixing copper sulfatehydrate (180 g), sulfuric acid (27 g) and ion exchanged water]. In thiscopper plating solution, an electrolytic copper electrode is dipped,followed by black copper plating by applying a voltage 3 V for threeminutes. A thickness of the copper layer was 1 micrometer. After that,the copper layer was dipped in a nickel plating solution [a solutionprepared in 1 L by mixing nickel sulfate hydrate (75 g), ammonium nickelsulfate (44 g), zinc sulfate (30 g), sodium thiocyanate (20 g) and ionexchanged water]. In this nickel plating solution, an electrolyticnickel electrode is dipped, followed by black nickel plating by applyinga voltage 3 V for one minute to form a black nickel layer with athickness of 1 micrometer on the copper layer. After that, calcinationwas performed at 600° C. to remove the residual resist layer material,thereby capable of obtaining blackened conductive fine patterns.

Example 7

3 g of acryl resin (E 2823, made by Elvacite) was dissolved in 1 g oftoluene and 0.2 g of butyl acetate to prepare a coating solution forscreen printing of a resist layer. The coating solution was screenprinted onto a glass substrate to form a resist layer pattern having athickness of 10 micrometers. Next, a region to be formed with blackenedconductive patterns was formed on the resist layer pattern using a UVlaser (made by UPI tech, product name: Xpress-DP) with a beam diameterof 20 micrometers. A critical dimension of the fine pattern was about 20micrometers, which is similar to the beam diameter of the laser. Next,the blackening solution composition prepared in Preparation Example 4was spin coated at 2500 rpm for 20 seconds to fill in the fine pattern,followed by drying at 200° C. to form a blackened layer with a thicknessof 1 micrometer. Next, the conductive ink composition prepared inPreparation Example 3 was spin coated at 2500 rpm for 20 seconds to fillin the fine pattern, followed by drying at 150° C. for two minutes. Athickness of the conductive patterns was 5 micrometers. After that, theformed fine pattern was black copper plated with an electroless copperplating solution containing 6.3 g/L of copper sulfate, 2.9 g/L offormaldehyde, 15.8 g/L of ethylenediaminetetraacetate (EDTA), 27 g/L ofcalcium hydroxide and 0.1 g/L of 2,2′-dipyridyl as an additive. Athickness of the copper layer was 1 micrometer. After that, calcinationwas performed at 600° C. to remove the residual resist layer material,thereby capable of obtaining blackened conductive fine patterns.

Example 8

3 g of acryl resin (E 2823, made by Elvacite) was dissolved in 1 g oftoluene and 0.2 g of butyl acetate to prepare a coating solution forscreen printing of a resist layer. The coating solution was screenprinted onto a glass substrate to form a resist layer pattern having athickness of 10 micrometers. Next, a region to be formed with blackenedconductive patterns was formed on the resist layer pattern using a UVlaser (made by UPI tech, product name: Xpress-DP) with a beam diameterof 20 micrometers. A critical dimension of the fine pattern was about 20micrometers, which is similar to the beam diameter of the laser. Next,the blackening solution composition prepared in Preparation Example 4was spin coated at 2500 rpm for 20 seconds to fill in the fine pattern,followed by drying at 200° C. to form a blackened layer with a thicknessof 1 micrometer. Next, the conductive ink composition prepared inPreparation Example 3 was spin coated at 2500 rpm for 20 seconds to fillin the fine pattern, followed by drying at 150° C. for two minutes. Athickness of the conductive patterns was 5 micrometers. After that, theformed fine pattern was dipped in an aqueous solution of 50 wt %ammonium sulfide to blacken a surface of the fine pattern, followed bycalcination of 600° C. The material remained as the resist layer wasvaporized upon the calcination at 600° C., thereby capable of obtainingblackened conductive fine patterns by only washing using toluene.

INDUSTRIAL APPLICABILITY

The method for blackening conductive patterns according to the presentinvention has, unlike the conventional method using chemical etching,advantages that productivity is enhanced as the process steps issimplified, environmental problem such as disposal of an etchingsolution is not generated as chemical etching is not used, and highresolution patterns with and superior conductivity and blackened degreecan be fabricated. Also, it is possible to form not only single layerpatterns but also multilayer patterns upon the formation of thepatterns.

Those skilled in the art will appreciate that the conceptions andspecific embodiments disclosed in the foregoing description may bereadily utilized as a basis for modifying or designing other embodimentsfor carrying out the same purposes of the present invention. Thoseskilled in the art will also appreciate that such equivalent embodimentsdo not depart from the spirit and scope of the invention as set forth inthe appended claims.

1. A method for fabricating blackened conductive patterns, comprising:(i) forming a resist layer on a non-conductive substrate; (ii) formingfine pattern grooves in the resist layer using a laser beam; (iii)forming a mixture layer containing a conductive material and ablackening material in the fine pattern grooves; and (iv) removing theresist layer remained on the non-conductive substrate.
 2. The method asset forth in claim 1, wherein the mixture layer is formed by filling aconductive ink containing a conductive material and a blackeningmaterial in the fine pattern grooves.
 3. The method as set forth inclaim 1, wherein the mixture layer is formed by forming a conductivelayer by filling and drying a conductive ink containing a conductivematerial in the fine pattern grooves and forming an upper blackenedlayer on the conductive layer.
 4. The method as set forth in claim 1,wherein the mixture layer is formed by forming a lower blackened layerby filling and drying a blackening solution containing a blackeningmaterial in the fine pattern grooves, forming a conductive layer byfilling and drying a conductive ink containing a conductive material inthe fine pattern grooves formed with the lower blackened layer, andforming an upper blackened layer on the conductive layer.
 5. The methodas set forth in claim 3, wherein the upper blackened layer is formed byfilling and drying a blackening solution containing a blackeningmaterial in the fine pattern grooves formed with the conductive layer.6. The method as set forth in claim 4, wherein the upper blackened layeris formed by filling and drying a blackening solution containing ablackening material in the fine pattern grooves formed with theconductive layer.
 7. The method as set forth in claim 3, wherein theupper blackened layer is formed by electroplating or electroless platingthe blackening material on the conductive layer.
 8. The method as setforth in claim 4, wherein the upper blackened layer is formed byelectroplating or electroless plating the blackening material on theconductive layer.
 9. The method as set forth in claim 3, wherein theupper blackened layer is formed by dipping the conductive layer formedin the fine pattern grooves in a blackening solution containing theblackening material to blacken the surface of the conductive layer. 10.The method as set forth in claim 4, wherein the upper blackened layer isformed by dipping the conductive layer formed in the fine patterngrooves in a blackening solution containing the blackening material toblacken the surface of the conductive layer.
 11. The method as set forthin claim 1, wherein, in the step (ii), the fine pattern grooves areformed by removing the resist layer and some of the substrate.
 12. Themethod as set forth in claim 11, wherein a depth of the substrateremoved in the step (ii) and a height of the mixture layer containingthe conductive material and the blackening material formed in the step(iii) are equal to each other.
 13. The method as set forth in claim 1,wherein the resist layer is made of an organic polymer material.
 14. Themethod as set forth in claim 13, wherein the organic polymer material isselected from the group consisting of polypropylene, polycarbonate,polyacrylate, polymethylmethacrylate, cellulose acetate, polyvinylchloride, polyurethane, polyester, alkyd resin, epoxy resin, melamineresin, phenol resin, phenol modified alkyd resin, epoxy modified alkydresin, vinyl modified alkyd resin, silicone modified alkyd resin,acrylic melamine resin, polyisocyanate resin and epoxy ester resin. 15.The method as set forth in claim 1, wherein the blackening material is ametal oxide, a metal sulfide or an organic metal compound containing oneor more than two metal(s) selected from the group consisting of Cu, Zn,Ni, Co, Ti, Mn, Fe, Cr, Nb, Ru, Cd, Ge and Sn.
 16. The method as setforth in claim 2, wherein the conductive material is selected from thegroup consisting of silver, gold, platinum, palladium, copper, nickel,zinc, iron, aluminum and a mixture thereof.
 17. The method as set forthin claim 3, wherein the conductive material is selected from the groupconsisting of silver, gold, platinum, palladium, copper, nickel, zinc,iron, aluminum and a mixture thereof.
 18. The method as set forth inclaim 4, wherein the conductive material is selected from the groupconsisting of silver, gold, platinum, palladium, copper, nickel, zinc,iron, aluminum and a mixture thereof.
 19. The method as set forth inclaim 1, wherein the conductive material is selected from the groupconsisting of silver, gold, platinum, palladium, copper, nickel, zinc,iron, aluminum and a mixture thereof.
 20. The method as set forth inclaim 2, wherein the conductive material is selected from the groupconsisting of silver, gold, platinum, palladium, copper, nickel, zinc,iron, aluminum and a mixture thereof.
 21. The method as set forth inclaim 3, wherein the conductive material is selected from the groupconsisting of silver, gold, platinum, palladium, copper, nickel, zinc,iron, aluminum and a mixture thereof.
 22. The method as set forth inclaim 4, wherein the conductive material is selected from the groupconsisting of silver, gold, platinum, palladium, copper, nickel, zinc,iron, aluminum and a mixture thereof.
 23. The method as set forth inclaim 19, wherein the conductive material includes silver particlesprepared by the following fabrication method: a) forming a silvercomplex by reacting a silver compound represented by the formula 1 belowwith one or a mixture of two or more selected from the group consistingof ammonium carbamate compound, ammonium carbonate compound and ammoniumbicarbonate compound represented by the formula 2 to 4 below; and b)preparing silver nanoparticles by reducing or thermally decomposing thesilver complex prepared in the step a) by reacting the silver complexwith a reducing agent or applying heat to the silver complex,

wherein, in the formulas 1 to 4, X is a substituent selected from thegroup consisting of oxygen, sulfur, halogen, cyano, cyanate, carbonate,nitrate, nitrite, sulfate, phosphate, thiocyanate, chlorate,perchlorate, tetrafluoroborate, acetylacetonate, carboxylate andderivatives thereof, n is an integer from 1 to 4, and R₁ to R₆ areindependently selected from the group consisting of hydrogen, hydroxylgroup, C₁-C₃₀ alkoxy group, C₃-C₂₀ aryloxy group, C₁-C₃₀ aliphatic orC₃-C₂₀ cycloaliphatic alkyl group or C₃-C₂₀ aryl or C₄-C₃₀ aralkyl groupas a mixture thereof, substituted C₁-C₃₀ alkyl group, substituted C₁-C₂₀aryl group, substituted C₄-C₃₀ aralkyl group, C₃-C₂₀ heterocycliccompound including a heteroatom selected from the group consisting of N,S, O, polymer compound and derivatives thereof, wherein when R₁ to R₆are substituted or unsubstituted alkyl group or aralkyl group, alkylgroup or aralkyl group may contain a heteroatom selected from the groupconsisting of N, S, O or an unsaturated bond in the carbon chain,wherein R₁ and R₂ or R₄ and R₅, independently, may form an alkylene ringcontaining or not containing a heteroatom.